The Stem Of Flowering Olant

Figure 8.Q Representative drupes. A. Peaches. B. Almonds. C. Olives.

contains a watery endosperm (see Chapter 23) commonly but incorrectly referred to as "milk." It is surrounded by the thick, hard endocarp typical of drupes. Other examples of drupes include the stone fruits (e.g., apricots, cherries, peaches, plums, olives, and almonds). In almonds, the husk, which dries somewhat and splits at maturity, is removed before marketing, and it is the endocarp that we crack to obtain the seed.

Berry Berries usually develop from a compound ovary and commonly contain more than one seed. The entire pericarp is fleshy, and it is difficult to distinguish between the mesocarp and the endocarp (Fig. 8.10). Three types of berries may be recognized.

A true berry is a fruit with a thin skin and a pericarp that is relatively soft at maturity. Although most contain more than one seed, notable exceptions are dates and avocados, which have only one seed. Typical examples of true berries include tomatoes, grapes, persimmons, peppers, and eggplants. Some fruits that popularly include the word berry in their common name (e.g., strawberry, raspberry, blackberry) botanically are not berries at all.

Chapter 8

Chapter 8

Types Grapes And Their Names
Figure 8.10 Representative berries. A. Grapes. B. Tomatoes.

Some berries are derived from flowers with inferior ovaries so that other parts of the flower also contribute to the flesh. They can usually be distinguished by the remnants of flower parts or their scars that persist at the tip. Examples of such berries include gooseberries, blueberries, cranberries, pomegranates, and bananas. Because fruit development in the cultivated banana is parthenocarpic, there are no seeds. Several other species of banana produce an abundance of seeds.

Pepos are berries with relatively thick rinds. Fruits of members of the Pumpkin Family (Cucurbitaceae), including pumpkins, cucumbers, watermelons, squashes, and cantaloupes, are pepos.

The hesperidium is a berry with a leathery skin containing oils. Numerous outgrowths from the inner lining of the ovary wall become saclike and swollen with juice as the fruit develops. All members of the Citrus Family (Rutaceae) produce this type of fruit. Examples include oranges, lemons, limes, grapefruit, tangerines, and kumquats.

Pome Pomes are simple fleshy fruits, the bulk of whose flesh comes from the enlarged floral tube or receptacle that grows up around the ovary. The endocarp around the seeds is papery or leathery. Examples include apples, pears, and quinces. In an apple, the ovary consists of the core and a little adjacent tissue. The remainder of the fruit has developed primarily from the floral tube, with a little tissue contributed by the receptacle (Fig. 8.11). Botany texts often refer to pomes, pepos, some berries, and other fruits derived from more than an ovary alone as accessory fruits or as fruits having accessory tissue.

Dry Fruits

Fruits whose mesocarp is definitely dry at maturity are classified as dry fruits.

Dry Fruits That Split at Maturity (Dehiscent Fruits)

The fruits in this group are distinguished from one another by the way they split.

Follicle The follicle splits along one side or seam (suture) only, exposing the seeds within (Fig. 8.12). Examples include larkspur, columbine, milkweed, and peony.

Legume The legume splits along two sides or seams (Fig. 8.13). Literally thousands of members of the Legume Family (Fabaceae) produce this type of fruit. Examples include peas, beans, garbanzo beans, lentils, carob, kudzu, and mesquite. Peanuts are also legumes, but they are atypical in that the fruits develop and mature underground. The seeds are usually released in nature by bacterial breakdown of the pericarp instead of through an active splitting action.

Silique Siliques also split along two sides or seams, but the seeds are borne on a central partition, which is exposed when the two halves of the fruit separate (Fig. 8.14A). Such fruits, when they are less than three times as long as they are wide, are called silicles (Fig. 8.14B). Siliques and silicles are produced by members of the Mustard Family (Brassicaceae), which includes broccoli, cabbage, radish, shepherd's purse, and watercress.

Apple Ovary Wall Pedicels

endocarp seed vascular bundle in outer part of the ovary

Figure 8.11 Apples (representative of pomes). The bulk of the flesh is derived from the floral tube that grows up around the ovary.

endocarp seed vascular bundle in outer part of the ovary

Figure 8.11 Apples (representative of pomes). The bulk of the flesh is derived from the floral tube that grows up around the ovary.

Follicle Fruit
Figure 8.12 Follicles. A. Milkweed. B. Magnolia. The fruit of the magnolia is actually an aggregate fruit consisting of approximately 40 to 80 individual one-seeded follicles on a common axis. The follicles and axis fall from the tree as a unit.

Chapter 8

Chapter 8

Silique Images

Figure 8.14 A. A silique after it has split open. The seeds are borne on a central, membranous partition. B. Silicles of Lunaria (dollar plant).

Capsule Capsules are the most common of the dry fruits that split (Fig. 8.15). They consist of at least two carpels and split in a variety of ways. Some split along the partitions between the carpels, while others split through the cavities (locules) in the carpels. Still others form a cap toward one end that pops off and releases the seeds, or they form a row of pores through which the seeds are shaken out as the capsule rattles in the wind. Examples include irises, orchids, lilies, poppies, violets, and snapdragons.

Dry Fruits That Do Not Split at Maturity (Indehiscent Fruits) In this type of dry fruit, the single seed is, to varying degrees, united with the pericarp.

Achene Only the base of the single seed of the achene is attached to its surrounding pericarp. Accordingly, the husk (pericarp) is relatively easily separated from the seed. Examples include sunflower "seeds" (the edible kernel plus the husk constitute the achene) (Fig. 8.16), buttercup, and buckwheat.

Nut Nuts are one-seeded fruits similar to achenes, but they are generally larger, and the pericarp is much harder and thicker. They develop with a cup, or cluster, of bracts at their

Figure 8.14 A. A silique after it has split open. The seeds are borne on a central, membranous partition. B. Silicles of Lunaria (dollar plant).

base. Examples include acorns (Fig. 8.16), hazelnuts (filberts), and hickory nuts. Botanically speaking, many nuts in the popular sense are not nuts. We have already seen that peanuts are atypical legumes and that coconuts and almonds are drupes. Walnuts and pecans are also drupes, whose "flesh" withers and dries after the seed matures. Brazil nuts

Wheat PericarpWheat Pericarp

are the seeds of a large capsule, and a cashew nut is the single seed of a unique drupe. It appears as a curved appendage at the end of a swollen pedicel, which is eaten raw in the tropics or made into preserves or wine. Pistachio nuts are also the seeds of drupes.

Grain (Caryopsis) The pericarp of the grain is tightly united with the seed and cannot be separated from it (Fig. 8.16). All members of the Grass Family (Poaceae), including corn, wheat, rice, oats, and barley, produce grains (also called caryopses).

Chapter 8

Chapter 8

Wheat Pericarp
Berry Boosters

Berry Boosters

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Responses

  • ludovico
    What does the vascular bundles of a broccoli look like?
    7 years ago

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